I highly recommend checking out the diet board, there are some good diet gurus on there.
A couple of years ago, I dropped a ton of weight on the Atkins diet. Wasn't really up on the CKD/TKD diets at the time so I just went 20g carbs. I didn't feel it wasted any muscles, but I saw some pictures during that time and I looked emaciated. But it was better than the pictures of me pushing 300lbs. I have been doing low carb for the past 6 months, dropped 30lbs currently at 195 and keeping strength/muscle... but I am also on low dose deca/test cycle. I kickstarted the diet with Atkins for the first month, than changed to a TKD for a couple of months followed up by CKD for a couple of months. CKD/TKD takes a lot more planning than Atkins, you really need to plan out your meals and supplements i.e. RALA for carbups and etc.